Adhesive and method of making same



. Reissued Apr. 13, 1937 UNITED STATES PATENT OFFICE ADHESIVE AND METHODOF MAKING SAME Edward F. Christopher, Chicago, Ill., assignor toIndustrial Patents Corporation, Chicago, 11]., a corporation of DelawareNo Drawing. Original him 1,962,763, dated June 12, 1934, Serial No.649,233, December 28, 1932. ggigiifation for reissue June 1, 1936,Serial No.-

18 Claims. (c1. 134-23.9)

This invention relates to a new and improved will hydrolize, and giveoff objectionable ammonia composition of matter adapted for use as anadhesive, plastic massor coating material and suitable for numerouspurposes and use in yasives made from casein and urea, that in thosecases where it may be necessary or desirable, from thestandpoint'of-commercial practice, to subject the adhesive to heat, orto boil the adhesive alone or with other substances, that the ureafumes. Also an adhesive of casein and urea is subject to attack bycertain enzymes such as urease enzymes which contaminate the air and orbiuret, cyanuric acid is also formed and perhaps a small quantity ofammonia. and in addition, some ammonia salt of cyanuric acid. The

invention therefore contemplates the use of these substances incombination because in practice rious industrial processes. Thisinvention also produce by their attack, an undesirable decompo- 5relates to a novel process by which a composition sition of the urea.01' this invention maybe produced. Accordingly it is a further Object ofthis in- This compomtion of matter is characterized as vention toprepare an adhesive which possesses made from casein, and biuret andcyanuric acid. the advantages but is free from the objections It is anobject of this invention to prepare an stated for urea, whereby it isneutral but will not 10 adhesive from casein which is neutral. give offammonia fumes as above described and A further object is to preparesneutral casein will not be subject to attack by urease enzymes adhesivewhich may be utilized with or without 'with resulting decomposition ofthe urea cona hardening agent, such as an aldehyde, the use stituent.

of which will destroy the water solubility of the In furtherance of theabove stated objects, it 15 adhesive and render it more durable andresistant is also an object of the present invention to protodeterioration and attack by bacteria and the vide casein adhesives whichare transparent, free like. from odors, and adapted for variousindustrial It is a further object of this invention to prouses,particularly in connection with edible foodvide a casein adhesive whichis water soluble and stufls, wherein it is highly important that the gowhich may be prepared initially in solution as a adhesive be free from.odors or any other inliquid or paste or if desired, in the form of afluence that would contaminate or in any wise powder whichis sold dryand prepared for use, affect the food product. merely by the addition ofwater. These and other objects not specifically enu- It'has been wellknown prior to this invention 'merated are contemplated for thisinvention as that casein adhesives exhibit high adhesive propwillreadily appear to one skilled in the art as m'ties. 'However, inasmuchas casein is insoluble the following description proceeds. in water andits use heretofore has involved the The present invention is based uponthe disuse of alkalis, casein adhesives have been'uncovery that a clearneutral casein solution may suitable in many uses as substitutes forvegetable be readily produced by dissolving casein in an and animalglues; It is well known that alkalis aqueous solution of biuret, or morespecifically, tend to discolor and in many cases, destroy paper, biuret,cyanuric acid, and perhaps also, ammonia and other objects to which theadhesive is apsalts of cyanuric acid. Furthermore, either ren-- plied.Furthermore, many of these prior art net casein or acid casein may beused in the prepcasein adhesives are subject to destructive actionaration of this solution whereas heretofore, with a of bacteria when insolution, and the joints made alkaline solvents, only acid casein hasbeentherefrom are comparatively easily soluble inusable. Caseincompletely dissolves in a short water. time in the cold aqueous solutionof biuret and As an improvement over the casein adhesives cyanuric acidand although variable quantities 4o utilizing alkaline solutions asdissolvirm mediums, of casein may be employed with success, casein 40there is disclosed in Patent No. 1,725,805, Lanmay be'added in equalquantity by weight to the decker, issued August 27th, 1929, an adhesiveprequantity of biuret and cyanuric acid employed. pared from casein andurea. This preparation is It is to be understood that this inventionanimprovement over the alkali solutions in that it contemplates the useof pure biuret as the disisneutral and further, in that it is subject tobeing solving agent for the casein but inasmuch as 45 hardened orrendered water insoluble by the acpure biuret is relatively expensive'to obtain. it tion of an aldehyde so as to prevent the taking isintended that a mixture of biuret and cyanuric up of water such as mightsubject the casein to acid be employed. This mixture serves, admirthedestructive action of bacteria. ably in accomplishing the objects ofthis inven- The applicant has found however, with adhetion. It is wellknown that in the preparation acid and its ammonia salts and in its purestate with anequal degree of success.

Purely by way of example, this invention may be practiced by, first,preparing the dissolving re-agent for the casein by gradually heatingdry urea until it reaches a temperature of approximately 160 degrees C.At 132 degrees C. the urea melts and at from 150 to 170 degrees C. itdecomposes and gives oi! ammonia gas. After the urea hasmelted theproduct is agitated frequently while heating and the heating continuedfor several hours. The time required to raise the temperature to 160degrees C. depends upon the amount of urea used and the source of heatemployed. By way of illustration, when using approximately 1.5 pounds ofurea and utilizing an oil bath, the time required to raise thetemperature to 160 degrees C. is approximately two hours. Thereafter,heating of the urea is continued at between 150 to 1'70 degrees .C. forapproximately two hours longer whereby the total heat treatment isconducted for about four hours. At this point air is blown through themelted mass to remove any ammonia which may be present. .The meltedmixture so prepared which is known to contain biuret, cyanur'ic acid andammonia or ammonia salts of cyanuric acid is then poured onto a slab ortray and allowed to cool and harden. The dry, hard product is thenremoved and ground to a powder in which iorm it is ready for use inpreparing the casein solution.

The second step is the preparation of the casein solution. One preferredmethod involves the use of .100 parts by weight of casein (preferably'70 mesh) 100 parts of the dissolving re-agent prepared as abovedescribed, and 200 parts water.

The ingredients are first mixed and heated in a jacketed kettle or steambath to a temperature approaching but not above 100 degrees C. until asmooth, viscous solution is obtained. The solution is then allowed tostand untfl cool and to permit the escape of air which is incorporatedduring the mixing. This periodwill vary according to the treatmentemployed but if al- .lowed to stand without special treatment. the masswill be cooled and freed of air in approxi- 50 mately sixteen hours.

It is tobe understood that the adhesive is in vthe nature of a colloidalsuspension and accordingly the ingredients may be varied \throughout'wide limits whereby the invention is not to be restricted to anyexact proportions. In fact, it h found that with the dissolving re-agenthere specifled,'only a relatively small amount of casein need beemployed in order to give the adhesive 00 solution relatively highadhesive properties.

-'It is to be understood that the adhesive may be used for any and allcommercial and industrial purposes but it may be mentioned that it hasspecial usefulness in connection with the preparation of certain foodproducts such as for instance, the gluing of normal cellophane in makingartiiicial sausage casings or similar or analogous um.

Furthermore, according to the proportions em- 70 played in theconcentration of the solution, an

adhesive can be obtained of any desired consistency, such as arelatively thin liquid or a paste of substantial viscosity. Furthermore,it is entirely practical to prepare the solid ingreidientsintheiormofadrypowderwhichmay ao,sas

' they are found to give the desirable results here be sold on themarket as such and thereafter prepared for use by the addition of thedesired quantity of water. It is found that by the addition of water tothe dry, powdered ingredients, that the casein is caused to readilydissolve to form the desired adhesive composition.

In addition, the adhesive of this invention may be treated for thepurpose of altering its water solubility after its application or use,whereby the adhesive is rendered more stable and free from attack bybacteria or the like. This may be accomplished by reacting with analdehyde which acts chemically therewith todestroy the water solubilityof the adhesive.

The exact chemical reaction is not understood but it is known that thesolubility of the product can be materially reduced in this way. Thisoffers a substantial improvement over various prior, practices wherevarious different methods were attempted which in most cases, would onlypenetrate the edges of the applied adhesive.

In the present invention, when the adhesive is in the form of asolution, a solution of formaldehyde may be employed or when theadhesivfe is prepared as a dry powder, a solid polymer of formaldehyde,such as para-formaldehyde, may

be added to the'solid mixture. The presence of formaldehyde in themixture ofl'ers the advan tage of being thoroughly incorporatedthroughout theentire adhesive mass whereby its action upon the mixturein rendering it water insoluble is more completely and satisfactorilyeffected.

I claim:

1. An adhesive mixture comprising biuret, and water.

2. An adhesive, mixture comprising biuret, and aldehyde and water.

3. An adhesive mixture comprising biuret, formaldehyde and water.

4. An adhesive mixture comprising biuret, cyanurlc acid, and water.

5. An adhesive mixture comprising casein, biuret, cyanuric acid, analdehyde, and water.

6. An adhesive mixture comprising casein, biuret, cyanuric acid,formaldehyde, and water.

'7. A new composition of matter comprising a powdered mixture of caseinand biuret adapted to form a casein solution upon the addition of water.

8. A new composition of matter comprising a powdered mixture of casein,biuret and cyanuric acid adapted to form a casein solution upon theaddition of water.

9. A new composition of matter comprising a powdered mixture of casein,biuret, and an aidehyde adapted to form a casein solution upon theaddition of water.

10. A new composition of matter comprising a casein,

casein casein,

casein.

powdered mixture of casein, biuret, cyanuric' acid, and an aldehydeadapted to form a casein solution upon the addition of water.

11. A new composition of matter comprising a powdered mixture of casein.bluret. and formaldehyde adapted to form a casein solution upon theaddition of water.

12. A new composition of matter comprising a powdered mixture of casein,biuret, cyanuric acid, and formaldehyde, adapted to form a caseinsolution upon the addition of water.

13, The process of preparing a neutral casein solution, which consistsin dissolving biuret'in water. and then dissolving casein in thesolution so prepared.

14. The process of preparing a neutral casein solution, which consistsin dissolving bluret and cyanuric acid in water and then dissolvingcasein in the solution so prepared.

15. The process of preparing a neutral casein 5 solution, which consistsin dissolving biuret in water, and then dissolving casein in thesolution so prepared and finally hardening said adhesive by reactingwith an aldehyde.

16. The process of preparing a neutral casein 10. solution, whichconsists in dissolving biuret in water, and then dissolving casein inthe solution so prepared and finally hardening said adhesive by reactingwith formaldehyde.

17. The process oi preparinc a neutral casein solution, which consistsin dissolvinl biuret and cyanuric acid in water, and then dissolvin:casein in the solution so prepared and finally hardening saidadhesive-by reacting with an aldehyde.

18. The process of preparing a neutral casein 7 solution, which consistsin dissolving biuret and I cyanuric acid in water. and then dissoivin:casein in the solution so prepared and iinsiiy hardeninl said adhesiveby reacting with formaldehyde.

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